[ILUG] Query regarding LSI Sata Raid and Debian

[Gareth Eason]

	I would be genuinely surprised if this card allows arbitrary expansion 
of a RAID5 array. It may force you to use RAID4 (which is easily 
expandible) and it almost certainly will allow online expansion of RAID0 
and/or RAID1 (though even RAID1 can be striped for performance, meaning 
expansion may lose you performance as measured against a similar setup 
that started out with the same number of drives using striped RAID1.)

	In short, if you want expandible RAID5 specifically, do ask the 
supplier exactly that before parting with your cash. I am highly suspect 
that it will not do it.

	In your case, a striped RAID1 (if you don't need the capacity) sounds 
like the bees nads (as it were) - since if you're running an FTP server 
I'm assuming you'll be handling primarily uplink traffic (from the POV 
of the server?)

	Just my cúpla pingin. YMMV, usual dislaimers apply, IANAL, etc. :-)

	Best regards,
	-->Gar



John Coleman wrote:
> On Thu, 21 Oct 2004 11:41:49 +0100, Gareth Eason <bigbro at skynet.ie> wrote:
> 
>>        Will it allow you to expand a RAID5 array? If so, it must be doing
>>something clever(tm)
>>
>>        Regards,
>>        -->Gar
>>
>>
> 
> From: http://www.lsilogic.com/products/serial_ata_raid/1506064.html
> 
> <quote>
> Features:
>  FlexRAID®:
>     -Online RAID level migration
>     -Online capacity expansion
> 
> </quote>
> 
> That sounds like "pop in another 250gig drive and let it expand the
> array" to me :)
> Am I incorrect in my interpretation?
> 
> From: http://www.linuxmafia.com/faq/Hardware/sata.html
> "LSI Logic MegaRAID SATA 150-4 (four ports) and 150-6 (six ports)
> Serial ATA RAID Host Adapters — work with 2.4.x kernel's megaraid2
> driver (same one as for SCSI). Cards use an Intel GC80302 dedicated
> I/O processor. This chipset, under its former AMI brand name, has had
> a long and excellent history with SCSI gear. Real hardware RAID.
> Optional battery backup unit is available for the model 150-6 card's
> cache, for more reliable operation in the event of power loss, etc.
> These cards should not be confused with the low-end LSI Logic MegaRaid
> SATA 150-2 card (which please see)."
> 
> I looked at the Adaptec stuff, but I wasn't impressed by it's
> performance compared to the 3Ware and LSI kit.
> 
> The main job for this array will be as a high-demand FTP server and
> Samba server.
> 
> I'm getting the 6-port card because it allows more flexibility and room to grow.
>